{"schema_version":"1.2","pwsid":"IL1350150","system_name":"COFFEEN","city":"AVISTON","state":"IL","population_served":647,"source_type":"SW","summary":"COFFEEN serves approximately 647 people in AVISTON, Illinois. Based on contaminant analyses from DNR, WQP, EPA ECHO, the most recent monitoring readings are within federal EPA standards (MCL), but this system has active MCL violations on record for 1 contaminant. 0 contaminants exceed health-based guidelines. Data is drawn from source-level compliance monitoring and covers 2000 through 2026. Results reflect conditions at the point of collection (wells, treatment plants), not necessarily at the tap.","data_period":{"start":"2000-10-26","end":"2026-08-11"},"contaminants_tested":3,"contaminants_detected":3,"exceedances":0,"guideline_exceedances":0,"contaminants":[{"name":"Haloacetic Acids (HAA5)","code":"2456","cas_number":null,"group":"dbps","section":"other_detected","measured_value":9.41,"unit":"ug/L","sample_date":"2026-08-11","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.0001,"health_guideline_source":"EWG Health Guideline","epa_mcl_value":0.06,"status":"below_limits","detection_limit":null},{"name":"Total Trihalomethanes (TTHMs)","code":"2950","cas_number":null,"group":"dbps","section":"other_detected","measured_value":13.42,"unit":"ug/L","sample_date":"2026-08-11","source":"DNR","source_scope":"source_monitoring","health_guideline_value":0.00015,"health_guideline_source":"EWG Health Guideline","epa_mcl_value":0.08,"status":"below_limits","detection_limit":null},{"name":"Nitrate (as N)","code":"NITRATE","cas_number":"14797-55-8","group":"inorganics","section":"other_detected","measured_value":2.6,"unit":"mg/L","sample_date":"2015-07-24","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":10,"health_guideline_source":"EPA MCLG","epa_mcl_value":10,"status":"below_limits","detection_limit":null},{"name":"Fluoride (natural)","code":"FLUORIDE","cas_number":"16984-48-8","group":"inorganics","section":"other_detected","measured_value":0.17,"unit":"mg/L","sample_date":"2015-07-15","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":4,"health_guideline_source":"EPA MCLG","epa_mcl_value":4,"status":"below_limits","detection_limit":null},{"name":"Arsenic","code":"ARSENIC","cas_number":"7440-38-2","group":"inorganics","section":"other_detected","measured_value":1.4,"unit":"ug/L","sample_date":"2015-07-15","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":0.000004,"health_guideline_source":"OEHHA PHG","epa_mcl_value":0.01,"status":"exceeds_guideline","detection_limit":null},{"name":"Barium","code":"BARIUM","cas_number":"7440-39-3","group":"inorganics","section":"other_detected","measured_value":0.272,"unit":"mg/L","sample_date":"2015-07-15","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":1,"health_guideline_source":"OEHHA PHG 2003 (hypertension endpoint)","epa_mcl_value":2,"status":"below_limits","detection_limit":null},{"name":"Chromium (total)","code":"CHROMIUM","cas_number":"7440-47-3","group":"inorganics","section":"other_detected","measured_value":0.12,"unit":"ug/L","sample_date":"2005-09-07","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":0.1,"health_guideline_source":"EPA MCLG","epa_mcl_value":0.1,"status":"below_limits","detection_limit":null},{"name":"Lead (90th Percentile)","code":"PB90","cas_number":"7439-92-1","group":"lead_copper","section":"other_detected","measured_value":0,"unit":"mg/L","sample_date":"2022-12-31","source":"EPA ECHO","source_scope":"federal_program","health_guideline_value":0.0002,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null},{"name":"Copper (90th Percentile)","code":"COPPER","cas_number":"7440-50-8","group":"lead_copper","section":"other_detected","measured_value":11.9,"unit":"ug/L","sample_date":"2015-07-15","source":"WQP","source_scope":"regional_groundwater","health_guideline_value":0.3,"health_guideline_source":"OEHHA PHG","epa_mcl_value":null,"status":"below_limits","detection_limit":null}],"sources":[{"name":"DNR","url":"https://apps.dnr.wi.gov/dwsportalpub"},{"name":"WQP","url":"https://www.waterqualitydata.us/"},{"name":"EPA ECHO","url":"https://echo.epa.gov/"}],"pfas_combined_display":null,"well_counts":{"active":0,"retired":0,"facilities_synced_at":"2026-10-26T01:13:06.376Z"},"historical_wells":[],"has_only_historical_data":false,"pfas_hazard_index":null,"tthm_lraa":[{"monitoring_point":"Well S2HT1","value":13.42,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":4,"mcl":80,"exceeds_mcl":false},{"monitoring_point":"Well S2HH1","value":13.93,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":4,"mcl":80,"exceeds_mcl":false}],"haa5_lraa":[{"monitoring_point":"Well S2HH1","value":9.41,"unit":"ug/L","quarters_used":["2025Q4","2026Q1","2026Q2","2026Q3"],"sample_count":4,"mcl":60,"exceeds_mcl":false}]}